The study sample comprised 498,043 men and women ages 40 to 69. All participants received physical examinations and provided blood, urine, and saliva samples when they enrolled in the study from 2006 to 2010.
They then completed a baseline questionnaire about their tea drinking habits. Participants recorded how many cups of tea—on average—they drank each day and whether they drank their tea very hot, hot, or warm. They were then followed up for a median of 11.2 years.
The researchers also recorded data on all participants’ diet, lifestyle, health, ethnicity, and socioeconomic status. They adjusted mortality data to take these factors into account.
Almost 85% of participants reported drinking tea, with 89% drinking black tea. Most of those who drank tea had between two and five cups per day, with 19% drinking more than six cups daily.
Heavy tea drinkers in the study were more likely to be smokers, have poorer general health and eat more red and processed meat, which may increase mortality.